Global Navigation Satellite System (GNSS) devices (which include, among other things, global positioning system (GPS) devices) are subject to various types of malicious attacks. One such attack is known as a man-in-the-middle (MITM) attack where the malicious party or attacker might receive a legitimate GNSS signal and then transmit an illegitimate GNSS signal to the intended recipient devices (e.g., spoofing the original GNSS signal). In other attacks, the malicious attacker may generate an illegitimate GNSS signal. Thus, in one form or another, the recipient devices receive an illegitimate signal and mistakenly believe that to be an authentic signal (or a GNSS signal from a legitimate GNSS satellite). Using these and other similar techniques, the malicious attacker may disseminate inaccurate GNSS signal data to one or more GNSS recipient devices. Modern GNSS chipsets receive and use GNSS data from three or four different satellites to calculate GNSS position. When one or more of these GNSS signals is spoofed (providing inaccurate data), the recipient GNSS chipset may determine an incorrect position, an incorrect heading, or both. In some instances, the magnitude of this error may be substantial and place the user of the recipient device in dangerous scenario.
Thus, a countermeasure is needed so that the recipient device can determine an accurate position and/or heading during a malicious attack.